I've received the contribution adjustment letter: what do I do now

If you’re an autónomo (self-employed worker) and you’ve received a letter from the Tesorería General de la Seguridad Social (the Spanish Social Security treasury) with an amount you weren’t expecting, take a breath. You’re not alone and it’s not a fine. It’s the contribution adjustment (regularización de cuotas), a new process that affects all self-employed workers since the system of contribution by real income came into force.

This guide explains what that letter means, how the difference they’re claiming from you (or that they owe you) is calculated, and above all how to stop it catching you off guard again next year.

The system of contribution by real income

Since January 2023, autónomos no longer freely choose their contribution base. The new system establishes 15 brackets of monthly net earnings, and each bracket has a minimum and maximum contribution associated with it. The idea is simple: you contribute in proportion to what you actually earn, like employees do.

The problem is that a self-employed worker’s income varies month to month and year to year. Nobody knows in January how much they’ll earn in December. So the system works with a provisional estimate that you declare at the start of the year (or when you register), and a later adjustment once the Spanish Tax Agency (Agencia Tributaria) closes the real figures.

In practice:

1. Each month you pay a contribution based on the bracket you estimated yourself.
2. The following year, the TGSS cross-checks your data with your income tax return.
3. If your real net earnings were higher than estimated, they claim the difference.
4. If they were lower, they refund what you overpaid.

That cross-check is the adjustment.

What the letter you’ve received means

The adjustment letter contains three key pieces of data:

Your real net earnings for the tax year. This is the figure the TGSS obtains from your income tax return. It’s calculated as your total income minus deductible expenses, minus the self-employed contribution paid, divided by twelve months.

The bracket that applied to you. Based on those monthly net earnings, you’re assigned a bracket from the official table. Each bracket has a minimum contribution base and an associated contribution.

The difference from what you paid. If during the year you were contributing in a bracket lower than the one that applied to you, the accumulated difference over the twelve months is what they claim. If you contributed in a higher bracket, they refund you.

The brackets by year (2023-2026)

The system has a gradual transition until 2032: the table is adjusted every year. These are the brackets in force under the legislation already published. Each cell shows the minimum monthly contribution and, in parentheses, the minimum contribution base it’s calculated on (all in euros):

The base is set by law (the Royal Decree-Law 13/2022 for 2023-2025 and Order PJC/297/2026 for 2026). The contribution is that base multiplied by the self-employed worker’s contribution rate, which is around 31.5% in 2026 but isn’t a single figure for everyone: the Order sets common contingencies at 28.30% and occupational ones at 1.30%, and on top of that come cessation of activity, vocational training and the MEI (the intergenerational equity mechanism, 0.90% in 2026), coverages each worker holds to a different extent. That’s why the contributions in the table are indicative: yours may vary by a few cents depending on your coverages.

The part of the rate that changes from one year to the next is the MEI, which rises 0.10 points each year (from 0.60% in 2023 to 0.90% in 2026). That makes each bracket’s minimum contribution rise a little even when the base doesn’t change; in fact, the figures in the 2026 table match those of 2025, in a year of extended budgets (under Royal Decree-Law 3/2026).

Notice the transition: in the low brackets the contribution falls (from €234.51 in 2023 to around €205 in 2025-2026 in the first bracket), while in the high brackets it rises sharply (from €509.80 to €607.35 in the last one). The system pushes each self-employed worker to contribute more in proportion to what they actually earn.

How your net earnings are calculated

This is where many autónomos get the surprise. The net earnings the TGSS uses are not your gross billing. The official calculation is:

Net earnings = Income - Deductible expenses - Self-employed contribution paid

And then a generic deduction of 7% is applied (3% if you’re a corporate autónomo) on that result, before dividing by twelve months.

What matters: if your business did well and you billed more than you estimated at the start of the year, your net earnings rise and the bracket that applied to you was higher. The monthly difference multiplied by twelve can be a significant hit.

A concrete example (with the 2026 contributions): you estimated earnings of 1,200 euros a month (a contribution of around 300 euros), but your real earnings were 1,600 euros (a contribution of around 303 euros). The difference is just 3 euros a month, about 37 euros a year. Not much. But if you estimated 1,200 and it turns out your earnings were 2,500 euros a month (a contribution of around 427 euros), the difference is about 128 euros a month, more than 1,500 euros a year. And that stings.

What to do if you have to pay

If the letter says you owe money to the TGSS:

Check that the net earnings figure is correct. The TGSS takes it directly from your income tax return. If you think there’s an error, the problem is in the tax return, not in the letter. You’d have to amend the return first.

Check the months contributed. If you registered or deregistered during the year, the adjustment should only cover the months you were registered. Verify that they’re not charging you for months that don’t apply.

Pay within the deadline. You have one month from the notification to pay without a surcharge. If you can’t pay it all at once, you can request a deferral from the TGSS, although it generates interest.

Adjust your bracket for the current year. If your financial situation hasn’t changed, it’ll probably happen again. Log in to the Import@ss portal and change your contribution base to the bracket that really applies to you. You can do this up to six times a year.

What to do if they owe you money

If the adjustment comes out in your favour (you overpaid because your real earnings were lower than estimated):

The refund is automatic. You don’t have to request it. The TGSS pays it into the bank account they have associated with your affiliation number. The legal deadline is several months, but it usually arrives sooner.

Decide whether you want to lower your bracket. If last year you earned less than expected, you may earn less this year too. Check whether it makes sense to lower your contribution base so you don’t end up advancing money unnecessarily again.

Watch out for the implications. Contributing less means lower benefits (sick leave, retirement, cessation of activity). Don’t lower the bracket just to pay less if you can afford to keep it.

How to avoid the surprise next year

The underlying problem is not knowing how much you really earn until you close the year. And by then it’s too late. The solution lies in keeping a monthly track of your net earnings.

Calculate your net earnings every month. It doesn’t have to be to the cent. The month’s income minus the month’s deductible expenses minus the month’s contribution. That figure, accumulated and divided by the months elapsed, gives you your average monthly net earnings to date.

Compare with your current bracket. If halfway through the year you see that your average earnings already exceed the bracket you’re in, raise the base before the difference piles up. It’s better to pay 20 euros more a month than to receive a letter for 240 euros the following year.

Use the six annual changes. You can change your contribution base in Import@ss up to six times a year, taking effect on the first day of the following month. There’s no penalty for changing frequently.

Set aside a buffer. Even if you adjust your bracket, there can always be a deviation. Keeping one month’s contribution in reserve for the possible adjustment avoids the shock. And if you’re on the flat rate (tarifa plana), the contribution increase when it ends adds to this: it’s worth preparing your cash flow for that jump well in advance.

If you already track your recurring expenses with a good system, adding this control is just a matter of one more metric.

The most common mistake: staying in the minimum bracket

Many autónomos registered with the minimum bracket in 2023 and haven’t touched their base since. If your business has gone well, the accumulated adjustment over two or three years can be a serious blow.

It’s not a fine or a punishment. It’s simply that you’ve been paying less than what applied to you. But psychologically it feels like a fine when the letter arrives with a four-digit figure. If you want to see where the contribution fits within everything a self-employed worker pays, we have a breakdown of what’s left clean when billing 40,000 euros.

The best strategy is to keep adjusting during the year. An autónomo who reviews their bracket every quarter and adapts it to reality gets no surprises. An autónomo who forgets about the matter until the letter arrives always gets them.

Deadlines and calendar

A given year’s adjustment arrives the following year, once the Agencia Tributaria has processed all the income tax returns. The approximate calendar:

• April - June: the income tax campaign for the previous year.
• Second half of the year: the TGSS cross-checks data with the Agencia Tributaria.
• Autumn - winter: the adjustment letters arrive.

In other words, the adjustment for tax year 2025 arrives during the second half of 2026. And the one for tax year 2026 will arrive in 2027.

Resources for appealing

If you think the adjustment contains an error:

1. Review your income tax return for the year in question.
2. Check that the months of registration match those the TGSS calculates.
3. If the error is in the tax return, file a supplementary or amending return.
4. If the error is in the months or in the TGSS calculation, file an administrative appeal through the Social Security electronic office.
5. The deadline to appeal is one month from the notification.

How does Cuéntamo help with this?

The contribution regularisation catches you off guard when you don’t know where your real numbers are heading. If you keep a monthly view of your net income in Cuéntamo (revenue minus expenses, month by month), you reach the end of the year with a fair idea of which contribution bracket you’ll land in, instead of finding out when the adjustment arrives. And if you want to estimate that adjustment now, you can use our self-employed quota adjustment calculator.

And because the cash-flow forecast projects your balance into the future, you can anticipate the moment Social Security claims the difference and have that money set aside, rather than letting the charge take you by surprise. It’s the same idea we apply to the first quarterly payment in cash-flow forecasting for the self-employed.

Cuéntamo doesn’t file the appeal for you or replace the TGSS’s data, but it gives you the picture of your real income so you can understand where the regularisation comes from and see it coming.

Frequently asked questions

Is the contribution adjustment letter a fine?

No, it’s not a fine or a punishment. It’s the reconciliation between the contributions you paid during the year according to your estimate and the ones that applied to you according to your real net earnings, once the Agencia Tributaria closes the figures of your tax return.

Why are they claiming money from me if I’ve paid my contribution every month?

Because your monthly contribution is based on an estimate you declare at the start of the year. If your real net earnings were higher than estimated, you contributed in a bracket lower than the one that applied to you, and the accumulated difference over the twelve months is what they claim.

How long do I have to pay the adjustment?

You have one month from the notification to pay without a surcharge. If you can’t pay it all at once, you can request a deferral from the Tesorería General de la Seguridad Social, although it generates interest.

If they refund me money, do I have to request the refund?

No, the refund is automatic. The Social Security pays it into the bank account associated with your affiliation number, without you having to request anything.

How do I stop it happening again next year?

Keep a monthly track of your net earnings and compare it with your current bracket. If you see that your average earnings already exceed the bracket you’re in, raise the contribution base in Import@ss before the difference piles up: you can change it up to six times a year.

This article is checked against official sources and reviewed periodically. If you spot anything out of date, email us at [email protected].